Evaluation of Wireless Magnetometers for Vehicle Detection at Signalized Intersections

Wireless magnetometers for vehicle detection were evaluated at a signalized intersection at both stop bar and advance locations. The studied approach had three lanes, and for each lane one sensor was installed at the stop bar and one more at the advance zones. Loop detectors were installed at the same location of the magnetometers and were used as a pointer to identify potential detection errors. Initially, data was collected after the system was installed by the manufacturer. Then, the system setup was adjusted by the manufacturer based on the analysis of the initial data, and data was collected again. Results show that the most frequent error at the stop bar was false calls (5.6%–7.6% due to vehicles in adjacent lanes, and additional 7.8%–9.6% due to single vehicles placing multiple calls), and at the advanced zones it was missed calls (0.9% to 10% per zone). Stuck-on calls and dropped calls were very rare.